The present invention relates to a detector and, more particularly, a detector capable of detecting the presence of an object in non-contact manner by using radiation such as light beam.
An optical type detector wherein an object is detected by the change of light beam radiated, for example, can achieve high speed detection and has such preferable characteristic that non-contact detection can be achieved. Therefore, the field in which the optical type detector can be used has become wider including detections of number of goods on the goods shipping line, of liquid surface, of lable misalignment, etc. However, the power source section housed in the conventional optical type detector is designed to meet a preinformed power source. In the case where power source standards under which the optical type detector is used are different from one another, the optical type detector housing the power section designed to be suitable for a power source standard can not be used under other power source standards. The voltage of commercial power is different in almost every country and a plurality of kinds of power source section must be therefore used to be suitable for any of power source standards in countries to which products are exported. As the result, it becomes necessary that a plurality of kinds of optical type detector even same in detection characteristic but having power source sections different from one another in power source standards must be prepared, thus causing product maintenance and stock adjustment to be extremely troublesome. In addition, the optical type detector having the power not be used under DC power source standard. Even if only a single detection characteristic is needed, therefore, the user feels extremely difficult in using his detector or must buy a new different detector when the power source standard now employed is changed.
Further, the power source section in the conventional optical type detector includes a transformer and is designed to be applicable to two kinds of AC power source of AC 100 V and AC 200 V. However, the power source input range of transformer is narrow. The transformer having a standard of AC 100/200 V.+-.10%, for example, cannot be replaced by the one having a standard of AC 110/220 V.+-.10%. Various transformers must be therefore arranged in the power source section to meet various voltage standards. In addition, it is difficult to make smaller the shape and weight of transformer itself. Therefore, the detector in which the transformer is incorporated becomes large in shape and heavy in weight. On the other hand, a power source section having no transformer but a voltage limiting element is sometimes employed in the detector to eliminate these drawbacks. However, this voltage limiting element is substantially equivalent to a resistor and consumes excessive energy for itself in operation. The efficiency of power source section is thus lowered and heat corresponding to the energy consumed by the voltage limiting element is generated.